elec_cosines - Compute cosine of angle between electrode position vectors
Usage: [Cos] = elec_cosines(A,B)
A,B both Nx3 (X,Y,Z) electrode coordinates
assuming a common origin at (0,0,0)
COS cosine angle between each row of A & B
If A is Nx3 and B is Mx3, COS is NxM.
Note: For a complete cosine matrix, let A = B.0001 function [Cos] = elec_cosines(A,B) 0002 0003 % elec_cosines - Compute cosine of angle between electrode position vectors 0004 % 0005 % Usage: [Cos] = elec_cosines(A,B) 0006 % 0007 % A,B both Nx3 (X,Y,Z) electrode coordinates 0008 % assuming a common origin at (0,0,0) 0009 % COS cosine angle between each row of A & B 0010 % If A is Nx3 and B is Mx3, COS is NxM. 0011 % 0012 % Note: For a complete cosine matrix, let A = B. 0013 % 0014 0015 % $Revision: 1.3 $ $Date: 2005/07/13 00:22:57 $ 0016 0017 % Licence: GNU GPL, no implied or express warranties 0018 % History: 08/2001, Darren.Weber_at_radiology.ucsf.edu 0019 % 01/2004, Darren.Weber_at_radiology.ucsf.edu 0020 % cos(0) = 1, not cos(0) = 0 at line 43 ??? 0021 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 0022 0023 eegversion = '$Revision: 1.3 $'; 0024 fprintf('ELEC_COSINES [v %s]\n',eegversion(11:15)); 0025 0026 if isempty(A), error('Input matrix A is empty\n'); end 0027 if isempty(B), error('Input matrix B is empty\n'); end 0028 0029 As = size(A); 0030 if ~isequal(As(2),3), 0031 if isequal(As(1),3), A = A'; 0032 else error('Input matrix A should be Nx3 [x y z] coordinates\n'); 0033 end 0034 end 0035 Bs = size(B); 0036 if ~isequal(Bs(2),3), 0037 if isequal(Bs(1),3), B = B'; 0038 else error('Input matrix B should be Nx3 [x y z] coordinates\n'); 0039 end 0040 end 0041 0042 fprintf('...calculating cosines\n'); tic 0043 0044 for a = 1:size(A,1), Aa = A(a,:); A_len = norm(Aa); 0045 for b = 1:size(B,1), Bb = B(b,:); B_len = norm(Bb); 0046 0047 Cos(a,b) = dot(Aa,Bb) / (A_len * B_len); 0048 end 0049 end 0050 0051 t=toc; fprintf('...done (%6.2f sec)\n\n',t); 0052 0053 return